US President Joe Biden has warned that the world risks 'Armageddon' with the worsening conflict in Ukraine

The United States reaffirmed its commitment to defend "every inch" of NATO territory ahead of talks among defense ministers from the alliance on Thursday that will include closed-door discussions by its nuclear planning group.

U.S. Defense Secretary Lloyd Austin made the remarks affirming America's commitment to NATO's collective defense following repeated nuclear threats by Russian President Vladimir Putin amid battlefield setbacks in his nearly eight-month-long invasion of Ukraine.

"We are committed to defending every inch of NATO's territory -- if and when it comes to that," Austin said.

Austin spoke shortly before attending a meeting by NATO's Nuclear Planning Group, which is NATO's senior body on nuclear matters and handles policy issues associated with its nuclear forces.